A battery may explode for a number of reasons due to the ignition of an explosive atmosphere contained within a cell. Causes for this include both external and internal ignition sources.
In order to absorb an explosion pressure wave produced inside the battery, DE 42 32 960 has disclosed providing the underside of the battery cover with a mat composed of fibrous material.
In addition, U.S. Pat. No. 4,751,154 has disclosed filling the upper, empty battery chamber with a plastic foam whose compressibility is used to absorb the pressure wave of an explosion. It has turned out that these known embodiments do not sufficiently lessen the impact of internal explosions.